Instagram, owned by Facebook, will use the smartwatch to help users keep up with their closest friends through alerts as soon as they post a picture, Financial Times reported.

This is Instagram's first foray into wearable technology and it had so far stayed away from wearable devices, including Google's Glass headset and smartwatches.

But recreating its feed of pretty, magazine-like photographs for the Apple Watch's tiny screen prompted a complete rethink of its app, according to Instagram designer Ian Silber, to create "the simplest feed we could think of".

"I think the watch is really about quick information and notifications. With the Watch, it's about thinking about interactions in terms of seconds," Silber was quoted as saying.

Apple lays down strict guidelines of how to create apps for its new Watch, restricting what third-party developers can create using its tools, called Watchkit.

For instance, Instagram tried to transfer its smartphone app's feature of double-tapping an image to like it, but that feature is not available through Watchkit.

"Developing for the Watch is definitely fun but they kept it pretty scoped and limited. That's smart because it helps shape the types of apps that come out. You don't want an app with a ton of features on your watch... you want one screen that tells you the most important information," Silber said.